low ohm means what value ? should be below 1 ohm ,

possible the light,or fan or wire leakage .
disconnect the neutral of all lights and fan . neutral point just before the light .
connect back the neutral at the DB .
observe if trip

do inspection of the wires , connectors , see its secured good/ not broken / expose and not touchin light body .
check also the fan wire contacts secured and not touch fan body

you looking for any damage wire cover

takes time to DIY
isolate 1 by 1 of the circuit .


This post has been edited by Momo33: Aug 15 2024, 11:24 AM

the tester is a insulation tester or megger . shopee have but not sure quality

since you know its the wire loop for lights and fan can try DIY . to find where the fault is.

so faults can be in the wiring , connections , fan and lights

disconnect the fan inputs . L N E
and all those easy lights
check if rccb trip.

if you disconnect all devices and still trip ..then wiring have issue.
ensure all wiring not touch any case , and not damage .

its time consuming but if you have the time just DIY as above first.
I am assuming you have a multimeter cos need to check resistance of wire if need . disconnect the L N E at DB box .


wiring seldom fail cos the lights circuit dont carry heavy current to melt it.




This post has been edited by Momo33: Aug 15 2024, 02:28 PM

https://shopee.com.my/PRO%F0%9F%8F%A0UNI-T-...93-0f5e4fd36720



specs.
Range UT123
Certifications RoHS
Category ratings CAT III 600V
DC voltage (V) 600V ±(0.5%+2)

AC voltage (V) 600V ±(1%+3)

DC Current (A) 10A

AC Current (A) 10A

Resistance (Ω) 20MΩ ±(0.8%+2)

40MΩ

Temperature -40~300°C ±(1%+5)

-40~572°F ±(2%+6)

Capacitance (F) 4000μF

to visualise better some questions.

how old your wiring
what type of lighting on this loop ? fluorescent 4 feet? LED downlights or the leds bulb screw on type,
the LED is it 1 driver for multiple leds or ?
how many switches on this loop , LEDs.

the rccb trip can happen when none /light, fan is ON , ?
is the fan ON at that time ?
tryin to understand situation when rccb trip timing

example fan have coils . when in use heats get hot and the coils leak .... then trip.
this is my main suspect .

you need a test pen .
and a rubber gloves too .

there are also multimeter about 100 RM more solid if budget allows . check only sanwa and uni T brands.


This post has been edited by Momo33: Aug 16 2024, 06:49 AM

all the lights point is in the hall or go also outside car park or ? if outside check water leaks/ wet and all the power connect

all the lights neutral wire return to the DB on 1 wire ?

am thinkin how to check and if can break up the circuit . or know how the neutral wiring loop goes to the points.


the round ceiling light is fluorescent round ? if yes open check any loose/ bare contacts . try to disconnect both out from the loop at the power connect to the light . . check if rccb still trip

is any part of the wiring under a false ceiling ?

the neutral wire from DB goes point A and continues to point B and point C etc..
means at the power point connect / is a 3 point carrying L N E , you will see 2 wire connect together cos to continue the loop .

the idea is to break the neutral loop , by disconnecting them . mean 1 wire is connect , the other hang free. hence you break the neutral loop to exclude light further down the loop . for troubleshooting purpose .

Wireman found out there are 3 neutral cable looping at fan and one of it ohm lower than 0.1, so he disconnect the faulty neutral wire from the fan and ON RCCB and Main MCB. The RCCB works, but trip after couple of minutes, and he pull ON the RCCB again,.
>> its possible there are other wiring at higher that normal leakage . your rccb 30 mA too sensitive . house wiring is old and leak higher. Last time the standard "Old house" use 100mA .rccb.

Few of my applicants burned out with sound "boom" immediately when he ON the RCCB.
>> this i not sure why ..cos should not happen .
put ON rccb cause a small surge but appliances can handle this.

your appliance blowup IMMEDIATELY at rccb put ON or after some time ??

he install back the neutral cable at fan
>> the faulty N wire replace or ?

the main purpose of rccb is to protect human . Not appliance .
rccb do not have over current protection . you have MCB for this.

The Malaysian Tenaga recommendation is 100mA for main DB , 30mA for sockets , 10mA for water heater.
new house developer will put 100mA .
yes can use 30mA but the risk is more trips when the wiring get old and degrade. this depend also if the wiring is first grade cable or cheap one.

""I had checked with other PW4 wireman, if there is looping 3 cable on neutral, it mean more than 1 MCB sharing the neutral, simply disconnect neutral but didn't disconnect the live cable will cause short circuit and burn. Wireman should also check and disconnect the live cable.""
this explain above i find no logic. . if remove 1 neutral wire that part circuit will not function/ cos the wire loop is not close complete and current cannot flow. means that bulb not work .
its shuld not trip rccb. or blow any
example if 1 wire for your bulb accident get loose/ or broke that light dont work , and rccb will not trip . right.

my guess is he not connect/ tight 1 connection cause sparking , cause trip rccb .
my guess .